Krokinobacter rhodopsin 2 (KR2) was discovered as the first light-driven sodium pumping rhodopsin (NaR) in 2013, which contains unique amino acid residues on C-helix (N112, D116, and Q123), referred to as an NDQ motif. Based on the recent X-ray crystal structures of KR2, the sodium transport pathway has been investigated by various methods. However, due to complicated structural information around the protonated Schiff base (PRSB) region in the dark state and lack of structural information in the intermediates with sodium bound in KR2, detailed sodium pump mechanism is still unclear. Here we applied comprehensive low-temperature light-induced difference FTIR spectroscopy on isotopically labeled KR2 WT and site-directed mutant proteins (N112A, D116E, R109A, and R109K). We assigned the N-D stretching vibration of the PRSB at 2095 cm and elucidate the hydrogen bonding interaction with D116 (a counter ion for the PRSB). We also assigned strongly hydrogen-bonded water (2333 cm) near R109 and D251, and found that presence of a positive charge at the position of R109 is prerequisite for the pumping function of KR2.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.bbabio.2020.148190 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Testing mixed metal bimetallic, and monometallic, cryptates for electrocatalytic hydrogen evolution.
Dalton Trans
January 2025
Department of Chemistry and the MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Appropriately designed catalysts help to minimise the energy required to convert the energy-poor feedstock HO into energy-rich molecular H. Herein, two families of pyridazine-based cryptates, mononuclear [MLi](BF) and mixed metal dinuclear [MCuLi](BF) (M = Fe, Co, Cu or Zn; Li is the Schiff base cryptand made by 2 : 3 condensation of tris(2-aminoethyl)amine and 3,6-diformylpyridazine), are investigated as potential electrocatalysts for the hydrogen evolution reaction (HER) in MeCN with acetic acid as the proton source. The synthesis and structures of a new mixed metal cryptate, [ZnCuLi](BF), and the tetrafluoroborate analogue of the previously reported perchlorate salt of the mono-zinc cryptate, [ZnLi](BF)·0.
View Article and Find Full Text PDFAltering Lipid A Precursor Ion Types in the Gas Phase for In-Depth Structural Elucidation via Tandem Mass Spectrometry.
Anal Chem
January 2025
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States.
Lipid A, a well-known saccharolipid, acts as the inner lipid-glycan anchor of lipopolysaccharides in Gram-negative bacterial cell membranes and functions as an endotoxin. Its structure is composed of two glucosamines with β(1 → 6) linkages and various fatty acyl and phosphate groups. The lipid A structure can be used for the identification of bacterial species, but its complexity poses significant structural characterization challenges.
View Article and Find Full Text PDFNMR spectroscopic studies of chitin oligomers - Resolution of individual residues and characterization of minor amide cis conformations.
Carbohydr Polym
March 2025
Department of Molecular Sciences, Swedish University of Agricultural Sciences, Almas Allé 5, Uppsala 75651, Sweden. Electronic address:
Chitin is the second most abundant biopolymer in nature after cellulose and is composed of N-acetylglucosamine (GlcNAc) connected via β(1 → 4)-glycosidic bonds. Despite its prominence in nature and diverse roles in pharmaceutical and food technological applications, there is still a need to develop methods to study structure and function of chitin and its corresponding oligomers. Efforts have been made to analyse chitin oligomers by NMR spectroscopy, but spectral overlap has prevented any differentiation between the interior residues.
View Article and Find Full Text PDFA Simple and Rapid "Turn-On" Fluorescent Probe Based on Binuclear Schiff Base for Zn and Its Application in Cell Imaging and Test Strips.
Molecules
December 2024
High & New Technology Research Center of Henan Academy of Sciences, No. 56 Hongzhuan Road, Zhengzhou 450002, China.
A series of colorful binuclear Schiff bases derived from the different diamine bridges including 1,2- ethylenediamine (bis-Et-SA, bis-Et-4-NEt, bis-Et-5-NO, bis-Et-Naph), 1,2-phenylenediamine (bis-Ph-SA, bis-Ph-4-NEt, bis-Ph-5-NO, bis-Ph-Naph), dicyano-1,2-ethenediamine (bis-CN-SA, bis-CN-4-NEt, bis-CN-5-NO, bis-CN-Naph) have been designed and prepared. The optical properties of these binuclear Schiff base ligands were fully determined by UV-Vis absorption spectroscopy, fluorescence emission spectroscopy, and time-dependent-density functional theory (TD-DFT) calculations. The inclusion of D-A systems and/or π-extended systems in these binuclear Schiff base ligands not only enables adjustable RGB light absorption and emission spectra (300~700 nm) but also yields high fluorescence quantum efficiencies of up to 0.
View Article and Find Full Text PDFA neoteric smartphone-assisted colorimetric and fluorometric dual-mode probe based on anthraquinone derived Schiff base for wide-range pH and Cu/S determination in bioimaging.
Biosens Bioelectron
March 2025
School of Chemistry and Chemical Engineering, Institute of Environmental Science, Shanxi University, Taiyuan, 030006, PR China. Electronic address:
The fluctuation of ion content has an important effect on human health and ecological environment. Herein, a novel colorimetric and fluorescent dual mode probe (DMHB) has been designed via the imine bond bridging of anthraquinone derivative dye and salicyl hydrazide. The DMHB displays significance wide-range pH dependent spectral behavior (pKa 5.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!